Receiving apparatus, transmitting apparatus, and communication system

ABSTRACT

A receiving apparatus and transmitting apparatus capable of transmitting and receiving a high speed optical signal and a communication system using the same, including a transmitting apparatus having a conversion circuit for converting serially input data to a plurality of bits of parallel data given predetermined information and an LED array having a number of LED units corresponding to the number of bits of the parallel data from the conversion circuit arranged in an array, wherein the LED units are controlled in light emission in parallel based on bit information of corresponding parallel data to emit optical information signals dispersed in a spatially predetermined range, and of a receiving apparatus having a plurality of photo-diodes arranged in an array for emitting electric signals of levels in accordance with amounts of light received, wherein the photo-diodes output electric signals in parallel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/824,911filed Apr. 3, 2001, the disclosure of which is hereby incorporated byreference herein, and claims priority from Japanese Application No.2000-110557 filed Apr. 6, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a receiving apparatus and transmittingapparatus for receiving and transmitting data as information light and acommunication system using the same.

2. Description of the Related Art

As a communication system for transmitting data converted to opticalinformation, optical information transmission systems using opticalfibers as a transmission medium are in practical use.

In recent years, there has been remarkably progress in opticalcommunication technology. Transmission of various kinds of informationincluding image information by optical fibers is being realized to notonly trunk lines, but also the level of the general homes, by links tonot only telephone systems, but also computer networks.

The transfer rate has been improved enabling even communication at 100Mbps and further 200 Mbps or 400 Mbps (on the frequency level, agiga-(G) hertz order, for instance, 2.4 to 5 GHz).

Summarizing the problem to be solved by the invention, when transmittingvarious kinds of information including image information by opticalfibers to for example the general homes as explained above, thetransmitted information is delivered to a personal computer, television,telephone, etc. (hereinafter, referred to as data processingapparatuses).

In this case, when the information processing apparatus is installed inone place, it is possible to lay an optical fiber inside the home fortransfer of the optical information as it is to the informationprocessing apparatus for example via an optical repeater and convert theoptical information to an electric signal at the information processingapparatus side.

It is also possible to move the information processing apparatus aroundinstead of installing it in one place, however, this is not practical inthat it is then necessary to re-lay the optical fiber.

Use of wireless communication using radio waves can therefore beconsidered. Wireless communication is however only possible using thetens of Mbps to 100 Mbps range due to legal restrictions.

Accordingly, wireless communication cannot be applied for recent highspeed optical communication of 100 Mbps or more.

Therefore, it is considered practical to convert an optical signaltransmitted from the outside over an optical fiber to an electric signalby an optical repeater, convert the electric signal back to an opticalsignal to generate optical information (hereinafter, information light),and convert it back from an optical signal to electric signal at theinformation processing apparatus side.

A semiconductor laser and a light-emitting diode can be used foremitting information light, but a semiconductor laser is not preferabledue to problems of directivity etc.

Accordingly, it is preferable to use a light-emitting diode. There arehowever official restrictions on the strength, and therefore problemsremains in the strength per predetermined area. Under the currentcircumstances, construction of a communication system capable ofreliably transmitting and receiving a high speed optical signal isdifficult.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a receiving apparatusand a transmitting apparatus capable of reliably transmitting andreceiving a high speed optical signal and a communication system usingthe same.

According to a first aspect of the present invention, there is provideda receiving apparatus for receiving information light, comprising alight receiving element array comprised of a plurality of lightreceiving elements for outputting electric signals at levels inaccordance with amounts of light received arranged in an array, whereinthe light receiving elements output the electric signals in parallel andan information extraction circuit for receiving the plurality ofelectric signals output in parallel from the light receiving elementarray and extracting information in accordance with the informationlight based on the plurality of electric signals.

According to a second aspect of the present invention, there is provideda transmitting apparatus comprising a conversion circuit for convertingserially input data to a plurality of bits of parallel data respectivelygiving predetermined information and a light emitting diode arraycomprising light emitting diode units of at least a number correspondingto the number of bits of parallel data from the conversion circuitarranged in an array, wherein the respective light emitting diode unitsare controlled in light emission in parallel based on bit information ofthe corresponding parallel data to emit information light dispersed in aspatially predetermined range.

According to a third aspect of the present invention, there is provideda communication system comprising a transmitting apparatus fortransmitting information light and a receiving apparatus including alight receiving element array comprising a plurality of light receivingelements for outputting electric signals at levels in accordance withamounts of light received arranged in an array, wherein the respectivelight receiving elements output electric signals in parallel, and aninformation extraction circuit for receiving a plurality of electricsignals output in parallel from the light receiving element array andextracting information in accordance with the information light based onthe plurality of electric signals.

Also, according to the present invention, the receiving apparatus isfurther comprising an optical system for condensing the informationlight to a predetermined region of a light receiving region of the lightreceiving element array.

Also, according to the present invention, the optical system is capableof adjusting a position of a light axis direction based on a controlsignal; and the information extraction circuit outputs the controlsignal for adjusting a position of the light axis direction to theoptical system when information in accordance with the information lightcannot be extracted based on the plurality of electric signals.

Also, according to the present invention, a wavelength of theinformation light is a wavelength included in a visible range.

Also, according to the present invention, the information light includesa plurality of information corresponding to bits of plurality of bits ofparallel data and is dispersed in a spatially predetermined range.

Also, according to the present invention, an information extractioncircuit of the receiving apparatus comprises a binarizing circuit forbinarizing a plurality of electric signals by the light receivingelement array; a data selection circuit for selecting data correspondingto the information light from the plurality of binarized data from thebinarizing circuit; and a conversion circuit for decoding datacorresponding to an information light selected by the data selectioncircuit and converting it from parallel data to serial data.

According to a fourth aspect of the present invention, there is provideda communication system comprising a transmitting apparatus comprising aconversion circuit for converting serially input data to a plurality ofbits of parallel data respectively giving predetermined information anda light emitting diode array comprising light emitting diode units of atleast a number corresponding to the bits of parallel data from theconversion circuit arranged in an array, wherein the respective lightemitting diode units are controlled in light emission in parallel basedon bit information of the corresponding parallel data to emitinformation light dispersed in a spatially predetermined range; and areceiving apparatus including a light receiving element array comprisedof a plurality of light receiving elements for outputting electricsignals at levels in accordance with amounts of light received arrangedin an array, wherein the respective light receiving elements outputelectric signals in parallel, and an information extraction circuit forreceiving a plurality of electric signals output in parallel from thelight receiving element array and extracting information in accordancewith the information light based on the plurality of electric signals.

According to the present invention, information light, for example,having a wavelength included in a visible range is transmitted, forexample, from a transmitting apparatus.

The information light transmitted from the transmitting apparatus isirradiated on a predetermined region of a light receiving element arrayof a receiving apparatus via an optical system.

In the light receiving element array, a plurality of electric signals oflevels in accordance with the amounts of light received are generated byall of the light receiving elements including those in the region wherethe information light was received and are supplied to an informationextraction circuit.

In the information extraction circuit, information in accordance withthe information light is extracted based on the plurality of electricsignals output in parallel from the light receiving element array.

Also, according to the present invention, for example, serial data issupplied to a conversion circuit of the transmitting apparatus. Theserial data is given predetermined information, and converted to aplurality of bits of parallel data, and supplied to a light-emittingdiode array.

In the light-emitting diode array, the light-emitting diode units of thenumber corresponding to the number of bits of the parallel data from theconversion circuit are controlled in light emission in parallel based onbit information of the corresponding parallel data.

As a result, information light dispersed within a spatiallypredetermined range is emitted from the light-emitting diode array.

The information light dispersed within a spatially predetermined rangetransmitted from the transmitting apparatus is irradiated on apredetermined range of the light receiving element array of thereceiving apparatus, for example, via an optical system.

In the light receiving element array, a plurality of electric signals oflevels in accordance with the amounts of light received are generated byall of the light receiving elements including those in the region wherethe information light was received and are supplied to the informationextraction circuit.

In the information extraction circuit, the plurality of electric signalsfrom the light receiving element array are, for example, binarized in abinarizing circuit and supplied to a data selection circuit.

In the data selection circuit, data corresponding to the informationlight is selected from the plurality of binary data from the binarizingcircuit and supplied to a conversion circuit.

Then, in the conversion circuit, data corresponding to the informationlight selected by the data selection circuit is decoded, converted fromparallel data to serial data, and output.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clearer from the following description of the preferredembodiments given with reference to the accompanying drawings, in which:

FIG. 1 is a view of the system configuration of a first embodiment of acommunication system using a receiving apparatus and a transmittingapparatus according to the present invention;

FIG. 2 is a view for explaining a state of receiving information lightin the case of arranging a photo-diode array substantially right belowan LED array according to the present invention;

FIG. 3 is a view for explaining a state of receiving information lightin the case of arranging a photo-diode array obliquely below an LEDarray according to the present invention;

FIG. 4 is a view for explaining a transmission/receiving apparatus on anupside when constructing a communication system assuming a downlink anduplink; and

FIG. 5 is a view of the system configuration of a second embodiment of acommunication system using a receiving apparatus and a transmittingapparatus according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, an explanation will be made of embodiments of the presentinvention by referring to the drawings.

FIRST EMBODIMENT

FIG. 1 is a view of the system configuration of a first embodiment of acommunication system using a receiving apparatus and a transmittingapparatus according to the present invention.

A communication system 10 comprises a transmitting apparatus 20 and areceiving apparatus 30.

The transmitting apparatus 20 comprises a coding and serial to parallelconversion circuit 21 and an LED (light emitting diode) array 22.

The coding and serial to parallel conversion circuit (hereinafter,simply referred to as a conversion circuit) 21 performs predeterminedcoding on the input electric signal, that is, the serial data, toconvert it for example to a 16-bit parallel signal, outputs this to theLED array 22, and generates a signal S21 for driving the later explainedLED units of the correspondingly provided LED array 22 based on the bitinformation.

The conversion circuit 21 adds information, for example, correspondingto the logic “1” and “0”, at the time of coding.

The LED array 22 is configured, for example, by LED units (group) 22-1to 22-16 for emitting visible rays (wavelength range of about 380 nm to780 nm) arranged in a 44 matrix.

The number 16 of the LED units 22-1 to 22-16 corresponds to the numberof bits of the converted parallel data of the conversion circuit 21. TheLED units 22-1 to 22-16 are provided corresponding to the bits of theparallel data.

The LED units 22-1 to 22-16 are controlled in light emission inaccordance with a drive signal S21 from the conversion circuit 21, thatis, the bit information of the parallel data. The LED array 22 as awhole emits information light SOL dispersed within a spatiallypredetermined range.

Each of the LED units 22-1 to 22-16 is configured, for example, of agroup of light emitting portion of 100 LEDs. Therefore, in the presentembodiment, the LED array 22 is comprised using 1600 LEDs.

As the LEDs, for example, white LEDs used for illumination may beapplied.

In this case, the LED array 22 can be used as lighting equipment in theoffice or home and is for example placed on the ceiling of a room.

Accordingly, the transmitting apparatus 20 according to the presentembodiment is effective in a system for receiving informationtransmitted by using an optical communication technique and opticalfibers as a transfer medium at the office or the home. In this case, thedata input to the conversion circuit 21 of the transmitting apparatus isan electric signal converted from an optical signal in a not shownoptical repeater.

If it is possible to transmit information at the rate of 25 Mbps fromone LED unit in the LED array 22 of the present embodiment, this isequivalent to being able to transmit information light SOL correspondingto 400 Mbps from the entire 16 LED units.

Therefore, the transmitting apparatus 20 according to the presentembodiment can be sufficiently used for the recent high speed opticalcommunication of more than 100 Mbps, that is 200 Mbps and furthermore400 Mbps.

The receiving apparatus 30 comprises a photo-diode array 31 as a lightreceiving element array, a condenser lens 32 as an optical system, 256amplifiers 33 n (n=integer from 1 to 256), 256 binarizing circuits 34 n,a data selection circuit 35, and a parallel to serial conversion anddecoding circuit (hereinafter referred to as a conversion circuit) 36.

An information extraction circuit according to the present invention isconfigured by the amplifiers 33 n, binarizing circuits 34 n, dataselection circuit 35, and conversion circuit 36.

The photo-diode array 31 is comprised, for example, of 256 photo-diodesarranged in a 16×16 matrix and outputs 256 electric signals of levels inaccordance with amounts of light received from the photo-diodes at ahigh speed to the amplifiers 33 n provided correspondingly in parallel.

The condenser lens 32 condenses the information light SOL transmittedform the LED array 22 of the transmitting apparatus 20 to apredetermined region of the photo-diode array 31.

Due to the condenser lens 32, it is possible to reliably guide theinformation light SOL to a predetermined region of the light receivingportion of the photo-diode array 31 when of course the receivingapparatus 30 is placed immediately below the LED array 22 provided onthe ceiling, for example, as shown in FIG. 2, and even when theinformation light SOL is incident at an angle, for example, as shown inFIG. 3.

The amplifiers 33 n amplify in parallel corresponding electric signalsobtained by the photo-diodes of the photo-diode array 31 and output themto the correspondingly arranged binarizing circuits 34 n.

The binarizing circuits 34 n compare the electric signals from thecorresponding amplifiers 33 n with a predetermined threshold value tobinarizes them to “0” and “1” and outputs them to the data selectioncircuit 35.

The data selection circuit 35 receives the 256 bits of binarized datafrom the binarizing circuits 34 n, selects as parallel data 16 bits ofdata in accordance with the information light SOL corresponding to 16bits transmitted from the transmitting apparatus 20, and outputs them tothe conversion circuit 36.

The conversion circuit 36 decodes the 16 of bits data corresponding tothe information light SOL selected by the data selection circuit 35,converts them from parallel data to serial data, and outputs them.

Next, the operation of a communication system having the aboveconfiguration will be explained.

For example, an electric signal, that is, serial data, is supplied tothe conversion circuit 21 of the transmitting apparatus 20. In theconversion circuit 21, the input serial data are given predeterminedinformation, converted to 16-bit parallel data, and supplied to the LEDarray 22.

In the LED array 22, the LED units 22-1 to 22-16 of the numbercorresponding to the number of bits of the parallel data from theconversion circuit 21 are controlled in light emission in parallel basedon the bit information of the corresponding parallel data.

As a result, information light SOL dispersed in a spatiallypredetermined range is emitted from the LED array 22, for example,provided on the ceiling.

The information light SOL dispersed in a spatially predetermined rangetransmitted from the transmitting apparatus 30 is irradiated on apredetermined region of the photo-diode array of the receiving apparatus30 via the condenser lens 32.

In the photo-diode array 31, a plurality of electric signals (256 in thepresent embodiment) of levels in accordance with amounts of lightreceived are generated by all of the photo-diodes including the lightreceiving elements in the region receiving the information light SOL.

The 256 electric signals are generated in parallel, amplified by apredetermined gain by the corresponding amplifiers 33 n, and supplied tothe corresponding binarizing circuits 34 n.

In the binarizing circuits 34 n, the electric signals from thecorresponding amplifiers 33 n are compared with a predeterminedthreshold values, binarized to “0” and “1”, and they are output to thedata selection circuit 35.

In the data selection circuit 35, the 256 bits of binarized data fromthe binarizing circuits 34 n are received, 16 bits of data in accordancewith the information light SOL corresponding to 16 bits transmitted fromthe transmitting apparatus 20 are selected as parallel data, and theyare output to the conversion circuit 36.

Then, in the conversion circuit 36, the 16 bits of data corresponding tothe information light SOL selected by the data selection circuit 35 aredecoded, they are converted from parallel data to serial data, and areoutput.

As explained above, according to the present embodiment, since provisionis made of a transmitting apparatus 20 comprising a conversion circuit21 for converting serially input data to a plurality of bits of paralleldata given predetermined information and an LED array 22 comprised ofLED units of at least a number corresponding to the number of bits ofthe parallel data from the conversion circuit 21 arranged in an array,wherein the LED units are controlled in light emission in parallel basedon bit information of corresponding parallel data to emit informationlight SOL dispersed in a spatially predetermined range, and of areceiving apparatus 30 having a photo-diode array 31 comprised of aplurality of photo-diodes for emitting electric signals of levels inaccordance with amounts of light received arranged in an array, whereinthe photo-diodes output electric signals in parallel, for selectinginformation in accordance with the information light SOL based on theplurality of electric signals output in parallel from the photo-diodearray 31, converting the selected parallel data to serial data, andoutputting the same, it is possible to sufficiently use the inventionfor high speed optical communication of more than 100 Mbps, for example200 Mbps and furthermore 400 Mbps, and to reliably transmit and receivea high speed optical signal.

Note that needless to say the number of LED units of the LED array 22and the number of photo-diodes of the photo-diode array 31 are notlimited to those of the present embodiment.

Also, in a communication system, when assuming a downlink and uplink,the communication system of FIG. 1 corresponds to a downlink.

To construct a system including an uplink, for example, as shown in FIG.4, it is possible to transmit data to a receiving apparatus 42 providedon the ceiling etc. by using a transmitting apparatus using an infraredray.

SECOND EMBODIMENT

FIG. 5 is a view of the system configuration of a second embodiment of acommunication system using a receiving apparatus and a transmittingapparatus according to the present invention.

The point of difference of the second embodiment from the firstembodiment is that a zoom lens 32A is used as an optical system and thatwhen data in accordance with information light cannot be selected in adata selection circuit 35A, it is judged that the information light isnot being condensed on the photo-diode array 31 as desired (for example,the focus is off) and a control signal CTL is output to the zoom lens32A to adjust the focus.

According to the second embodiment, in addition to the effects of thefirst embodiment, there is an advantage that a further reliablereceiving operation can be realized.

Note that in the above first and second embodiments, a binarizingcircuit 34 was used, but of course this may also be a circuit forconverting to a multilevel signal. Also, it is possible to use theanalog value as it is.

Summarizing the effects of the invention, as explained above, accordingto the present invention, there is the advantage that a high speedoptical signal can be reliably transmitted and received.

While the invention has been described with reference to specificembodiment chosen for purpose of illustration, it should be apparentthat numerous modifications could be made thereto by those skilled inthe art without departing from the basic concept and scope of theinvention.

1. A communication system, comprising: a transmitting apparatus fortransmitting optical information in the form of a light beam dispersedin a spatially predetermined range formed by an array of a plurality oflight emitting diodes corresponding to a number of bits of parallelinput data, wherein a level of light emission from the plurality oflight emitting diodes is in accordance with bit information of theparallel input data; a receiving apparatus including a light receivingelement array having a plurality of light receiving elements arranged inan array for receiving the light beam and outputting a plurality ofelectric signals at levels corresponding to amounts of light received,wherein the light receiving elements output electric signals inparallel, and an information extraction circuit for receiving aplurality of electric signals output in parallel from the lightreceiving element array and extracting information in accordance withthe optical information signal based on the plurality of electricsignals, wherein the receiving apparatus comprises an optical system forcondensing the light beam to a predetermined region of a light receivingregion of the light receiving element array, and wherein the opticalsystem is capable of adjusting a position of a light axis directionbased on a control signal; and the information extraction circuitoutputs the control signal for adjusting the position of the light axisdirection to the optical system when information in accordance with theoptical information cannot be extracted based on the plurality ofelectric signals, wherein said optical information includes a pluralityof information corresponding to bits of a plurality of parallel data andis dispersed in a spatially predetermined range.
 2. The communicationsystem as set forth in claim 1, wherein a wavelength of the opticalinformation transmitted by said transmitting apparatus is within avisible wavelength range.
 3. The communication system as set forth inclaim 1, wherein the information extraction circuit of the receivingapparatus comprises: a binarizing circuit for binarizing the pluralityof electric signals from the light receiving element array; a dataselection circuit for selecting data corresponding to the opticalinformation from the plurality of binarized electric signals from thebinarizing circuit; and a conversion circuit for decoding datacorresponding to the optical information selected by said data selectioncircuit and converting it from parallel data to serial data.
 4. Thecommunication system as set forth in claim 1, wherein the informationextraction circuit of the receiving apparatus comprises: a binarizingcircuit for binarizing the plurality of electric signals from the lightreceiving element array; a data selection circuit for selecting datacorresponding to the optical information from the plurality of binarizedelectric signals from the binarizing circuit; and a conversion circuitfor decoding data corresponding to the optical information selected bythe data selection circuit and converting it from parallel data toserial data.